Brown Tips On Burning Bush - Knowledgebase Question

I have several burning bushes in the front of my house that have been doing great for about 2 1/2 years now. I just noticed that the tips of the leaves are turning brown, as well as the entire leaf in some cases. I use a drip irrigation system and keep up with watering, but I'm not sure what is happening. I recently srayed some Miracle Grow (4 days ago) on these bushes and we have had quite a bit of rain (midwest storms). Is it too much water or the fertilizer? What can I do? The other plants around them are doing just fine. Any help would be great!

Burniong bushes that brown on the tips would usually be signalling moisture stress, but if the soil has been evenly moist and the shrubs have rooted beyond their original planting holes, then this is probably not the problem. They could also be suffering "fertilizer burn" if the foliar feed was applied at a rate more generous that the label instructions.